/**
sass中支持6种主要数据类型：
 - 1.数字 1,2,3,4
 - 2.字符串，有引号和无引号字符串，'foo','bar',baz
 - 3.颜色：blue,#ccc,rgba(255,255,255,1)
 - 4.布尔值：true,false
 - 5.空：null
 - 6.数组(list):用空格或逗号做分隔符，1.4em 1em 2em,Helvetica,Arial,sans-serif
 - 7.maps相当于JS的Object,(k1:val1,k2:val2)
*/
$layer-index:10;
$border-width:30px;
$font-base-family:'Open Sans',Helvertical,Sans-serif;
$top-bg-color:rgba(255,147,29,0.6);
$block-base-padding:6px 10px;
$blank-mode:true;
$var:null;//值null是其类型的唯一值，它表示缺少值，通常函数返回以指示缺点结果
$color-map:(color1:red,color2:blue,color3:green);
$fonts:(self:'Helvetica Neue',monospace:'Consolas');

//默认值
$color:red !default;

.container{
    $font-size: 16px !global;
    font-size: $font-size;
    color:$color;
    @if $blank-mode {
        background-color: black;
    }
    @else{
        background-color: white;
    }
    content:type-of($var);
    content:length($var);
    color:map-get($color-map, color3);

}